Prism.languages.c = Prism.languages.extend('clike', {
    'class-name': {
        pattern: /(\b(?:enum|struct)\s+)\w+/,
        lookbehind: true
    },
    'keyword': /\b(?:_Alignas|_Alignof|_Atomic|_Bool|_Complex|_Generic|_Imaginary|_Noreturn|_Static_assert|_Thread_local|asm|typeof|inline|auto|break|case|char|const|continue|default|do|double|else|enum|extern|float|for|goto|if|int|long|register|return|short|signed|sizeof|static|struct|switch|typedef|union|unsigned|void|volatile|while)\b/,
    'operator': />>=?|<<=?|->|([-+&|:])\1|[?:~]|[-+*/%&|^!=<>]=?/,
    'number': /(?:\b0x(?:[\da-f]+\.?[\da-f]*|\.[\da-f]+)(?:p[+-]?\d+)?|(?:\b\d+\.?\d*|\B\.\d+)(?:e[+-]?\d+)?)[ful]*/i
});

Prism.languages.insertBefore('c', 'string', {
    'macro': {
        // allow for multiline macro definitions
        // spaces after the # character compile fine with gcc
        pattern: /(^\s*)#\s*[a-z]+(?:[^\r\n\\]|\\(?:\r\n|[\s\S]))*/im,
        lookbehind: true,
        alias: 'property',
        inside: {
            // highlight the path of the include statement as a string
            'string': {
                pattern: /(#\s*include\s*)(?:<.+?>|("|')(?:\\?.)+?\2)/,
                lookbehind: true
            },
            // highlight macro directives as keywords
            'directive': {
                pattern: /(#\s*)\b(?:define|defined|elif|else|endif|error|ifdef|ifndef|if|import|include|line|pragma|undef|using)\b/,
                lookbehind: true,
                alias: 'keyword'
            }
        }
    },
    // highlight predefined macros as constants
    'constant': /\b(?:__FILE__|__LINE__|__DATE__|__TIME__|__TIMESTAMP__|__func__|EOF|NULL|SEEK_CUR|SEEK_END|SEEK_SET|stdin|stdout|stderr)\b/
});

delete Prism.languages.c['boolean'];